Shock and/or vibration sensitive articles, such as computers, monitors, TV's, VCR's, radios, computer tape and disk drives, and other sensitive electronic equipment, require special packaging when shipped inside shipping cartons. Conventional carton packaging used to protect such articles includes paper, nuggets of expanded foam, preformed polystyrene foam or beads, etc. Ideally, the packaging absorbs and dissipates shocks and vibrations impinging the shipping carton to minimize the shocks and vibrations experienced by the fragile article.
More recently, manufacturers of shock/vibration sensitive articles have developed stringent shock dissipation requirements for packaging used to ship their products. For example, some manufacturers use “drop test” requirements, which dictate the maximum amount of g-force that the article packaged inside a carton can experience when the carton is dropped from a certain height. The drop test requirements typically include several g force values, depending upon which carton side, edge, and/or corner lands on the drop surface. Therefore, the carton packaging needs to adequately dissipate shocks induced from many directions.
As shock dissipation requirements become more complex, so too must the carton packaging. The performance of the carton packaging design must not only satisfy the shock dissipation requirements, but ideally should also be easily adaptable to change the shock dissipation performance since shock dissipation requirements can change for any given article, or are different from article to article.
To complicate the problem of selecting appropriate carton packaging, many articles now require protection against vibration as well. Therefore, shipping carton packaging should not only absorb shock forces to meet the above mentioned drop test requirements, but must also sufficiently absorb vibrations typically experienced by shipping cartons in transit.
Conventional carton packaging materials have proved inadequate to meet the more stringent shock and vibration absorption requirements for modern articles of commerce. In order to satisfy such requirements, large volumes of conventional carton packaging is required around the article. Voluminous packaging materials are expensive and take up excessive warehouse space before use and trash/recycling space after use. Further, larger shipping cartons are necessitated by the voluminous carton packaging, which are more expensive to purchase and to ship. The shock/vibration dissipation performance of paper, nugget and bead packaging materials can depend in large part on how the user actually packages the particular article. If a particular conventional carton packaging is deemed to provide inadequate shock/vibration protection, there is no predictable way to modify such packaging material to meet such shock/vibration dissipation requirements, except for adding more packaging material and increasing the shipping carton size.
More recently, unitary packaging structures have been developed that are made of flexible polymeric materials to allow shocks to dissipate through flexing of the structure walls. Examples of such unitary structures can be found in U.S. Pat. Nos. 5,226,543, 5,385,232, and 5,515,976. However, these unitary packaging structures are typically designed to dissipate shocks primarily in one direction and/or fail to provide adequate shock/vibration protection under the more stringent performance specifications from fragile article manufacturers. Further, such unitary packaging structure designs are not easily adaptable to predictably change their shock/vibration dissipation performance to meet new and/or changing specifications. For example, if a drop test indicates there is insufficient shock dissipation in one direction, there is no easy modification that can be made to predictably change the shock dissipation performance in that direction without unpredictably affecting shock/vibration dissipation performance in other directions.
U.S. Pat. No. 5,799,796 proposes a system for solving the aforementioned problems comprising a light, inexpensive unitary spring system end cap packaging structure that efficiently dissipates shocks and vibrations while using a minimal amount of carton space during use, and a minimal amount of storage space before and after use. The system can be adapted to meet a wide range of shock/vibration dissipation requirements without using voluminous amounts of material.
The unitary spring system end cap of '796 includes a platform portion dimensioned to support at least a portion of a shock/vibration sensitive article and a sidewall structure. The sidewall structure includes an inner wall having proximal and distal edges, where the distal edge is joined to the platform portion, an outer wall having upper and lower edges, and at least one spring system integrally joined to the proximal edge of the inner wall and the upper edge of the outer wall. The spring system spaces the inner wall from the outer wall. The spring system includes at least one flexible harmonic bellows forming a flexible ridge that, for example, can have an arcuate shape along the length of the sidewall structure. The outer wall extends below the distal edge of the inner wall so that the platform portion is supported above the lower edge of the outer wall.